Optoelectronic modules, such as optoelectronic transceiver or transponder modules, are increasingly used in electronic and optoelectronic communication. Some modules can be plugged into a variety of host networking equipment. Modules typically communicate with a printed circuit board of a host device by transmitting electrical signals to the printed circuit board and receiving electrical signals from the printed circuit board. These electrical signals can then be transmitted by the module outside the host device as optical signals.
Multi-source agreements (MSAs), such as the C Form-factor Pluggable (CFP) MSA and the Quad Small Form-factor Pluggable (QSFP) MSA, specify, among other things, housing dimensions for modules. Conformity with an MSA allows a module to be plugged into host equipment designed in compliance with the MSA.
Optical signals are typically generated within a transmitter optical subassembly (TOSA) of a module using a laser, such as a vertical cavity surface emitting laser (VCSEL) or a distributed feedback (DFB) laser. As data rates in modules increase, two or more lasers are often included in a single TOSA. However, as MSAs specify increasingly smaller module housing dimensions, there is less available space for multi-laser TOSAs within the module housing. In addition, multi-laser TOSAs are often relatively expensive and often suffer from relatively high optical loss.